AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Profiling Sources and Chemical Aging Effects on the Oxidative Potential of Organic Aerosol
SHUNYAO WANG, Karl Demmans, Jianjun Han, Manpreet Takhar, Zeng Rui, Peng Hui, Arthur W. H. Chan, University of Toronto
Abstract Number: 773 Working Group: From Aerosol Dosimetry and Toxicology to Health
Abstract Exposure to ambient particles is associated with numerous adverse health outcomes. However, due to the complex properties and dynamic evolution of organic aerosol (OA), its ability to cause oxidative stress (oxidative potential, or OP) and the corresponding adverse health outcomes remain poorly understood. Unlike the other indirect cellular and acellular OP measurements, electron paramagnetic resonance (EPR) can directly delineate the type and quantity of free radical species. As the least ambiguous method for free radical measurements, different spin trap techniques were applied to the EPR OP measurement. In this work, a direct free radical profile (types, abundances and their lifetimes) was derived for OA emerged from various sources. In addition to secondary organic aerosol (SOA) from specific biogenic and anthropogenic hydrocarbon precursors, high radical signals were found in cooking and wood-burning emissions, indicating the potential health impact from indoor cooking activity and wildfire events. Using naphthalene SOA (NSOA) as a model system, relative abundances of reactive oxygen species in aerosol evolved under various photochemical aging processes were compared and linked to the varied chemical composition measured by mass spectrometry. Within a single type of OA system, the EPR measured OP trend along with atmospheric aging processes was found to be consistent with OP results from other acellular and cellular measurements. Mixing effects of different OA compositions on the free radical production were also investigated. Our study provides insights into how the chemical composition and atmospheric formation process of ambient particles are related with its ability to cause oxidative stress and potential adverse health outcomes.